A hydraulic master brake cylinder is described in German Patent Application No. DE 10 2009 028 034 A1. The hydraulic master brake cylinder includes a primary piston component having a piston element, the primary piston component being movable with the aid of a driver braking force in such a way that a pressure chamber volume of a pressure chamber of the hydraulic master brake cylinder which is fillable with liquid is reducible. Furthermore, with the aid of a brake booster, a braking assisting force should also be exertable on the first primary piston component in such a way that the pressure chamber volume of the pressure chamber which is fillable with liquid is additionally reducible, also with the aid of the braking assisting force.